Creating an Observation Hallway

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This is a tutorial for Portal.
Introduction
Making bts (behind the scenes) style observation halls is a simple job. It takes little time, especially with prefabricated items.
Due to the highly detailed nature of observation rooms, this tutorial will be provided in images. Reading order is left to right, then down.

Tutorial
Texture the floor and walls, then copy the walls, resize to 64 and re texture (floor texture: tile/observation_tilefloor003a. wall textures: concrete/observationwall_001a for the wall that matches with the ceiling, concrete/observationwall_001b for the wall that matches with the floor. Typing only "observation" will show a more general list of observation hallways skins.)
Select the whole arch, and clip it square. Make it a func_detail.
Add a spotlight and a point_spotlight. Default values will work.
Add the doors. (I grouped a detailed frame and door with a skip brush [Clarify].